Preparation and characterization of CuZnAl catalysts by citrate gel process

CuZnAl catalysts with different Cu loading (1-23 wt%) and a Zn:Al atomic ratio nearly constant (Zn:Al congruent to 0.6), were prepared by the citrate sol-gel method and characterized by different techniques such as TG, BET, TPR, XRD and FTIR. The final structure obtained was strongly influenced by the calcination temperature and metal precursor composition. XRD and quantitative Rietveld revealed Zn and Al species were mainly incorporated into the normal spinet matrix and copper predominantly forms CuO. The formation of a ZnAl2O4 spinet was favored by increasing Cu amounts and/or by increasing calcination temperature (from 500 degrees to 700 degrees C). The spinel phase of the catalysts calcined at 700 degrees C, had a good thermal stability and it was preserved after TPR measurements. Under hydrogen atmosphere Cu2+ was fully reduced to Cu-0. Although the composition and the calcination temperature have a strong influence on the phase nature in CuZnAl catalysts, the reducibility of Cu species changes in a non significant way. (c) 2006 Elsevier Ltd. All rights reserved.